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KJ -> XJ rear disc swap rotor question

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Old Apr 28, 2022 | 04:43 PM
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Default KJ -> XJ rear disc swap rotor question

I swapped in 2005 KJ (liberty) rear disc set up on my 8.25 rear end.
I puuled the lug stubs off the Liberty axles, but they are too big diameter to fit the 2000 XJ axles.
So I bought and installed FRONT 2000 XJ lug studs, they are plenty long.
I noticed a problem when installing the Liberty rotors, While the center hole in the rotors fit the XJ axle center hub fine,, The wheel stud holes in the Liberty rotors are much larger than the XJ wheel studs.
The rotor has a good deal of rotational "slop" on the wheel studs.
I always remember rotors fitting tight on wheel studs with no slop.
Are there rotors with smaller wheel stud holes ??

Last edited by Slackdaddy; Apr 28, 2022 at 05:12 PM.
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Old Apr 28, 2022 | 07:45 PM
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Once you clamp it tight with the wheel, the slop in the wheel stud holes won't affect anything; the clamping force is what holds it in place...
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Old Apr 29, 2022 | 08:10 AM
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X2, that's a non-issue. Run it.
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Old May 1, 2022 | 01:25 PM
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The correct rotors are from a ZJ, with disc brakes of course. The years are 94 to 98.
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Old May 2, 2022 | 04:43 AM
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Thanks,
I did some digging.
You are correct, The ZJ rotors have considerably smaller lug stud holes compared to the KJ (Liberty)

Originally Posted by Big David
The correct rotors are from a ZJ, with disc brakes of course. The years are 94 to 98.
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Old Jul 28, 2022 | 01:18 PM
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Originally Posted by Big David
The correct rotors are from a ZJ, with disc brakes of course. The years are 94 to 98.
Originally Posted by Slackdaddy
Thanks,
I did some digging.
You are correct, The ZJ rotors have considerably smaller lug stud holes compared to the KJ (Liberty)
So, with the disc set-up from a KJ with the XJ front lug studs, if I were to order new rotors, the best bet is to order the 94-98 ZJ rotors. My order is now complete! Thank you!
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Old Jul 28, 2022 | 11:30 PM
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Originally Posted by MrTodd
So, with the disc set-up from a KJ with the XJ front lug studs, if I were to order new rotors, the best bet is to order the 94-98 ZJ rotors. My order is now complete! Thank you!
But KJ backing plates, ZJ ones work but you need to grind out the insde
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Old Jul 29, 2022 | 07:03 AM
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Originally Posted by XJChang
But KJ backing plates, ZJ ones work but you need to grind out the insde
Yes. And not much at all. A sanding drum would likely work just fine.
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Old Jul 29, 2022 | 10:55 AM
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^ I used one on my Dremel. Just keep trying the fit until it's good. Would be easy to take off too much.
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Old Jul 29, 2022 | 11:13 AM
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Why would anyone go with the ZJ/WJ backing plates when the KJ plates fit without modifying? I went to the local Pick & Pull, found a 2006 KJ, pulled the calipers, backing plate w/bracket and e-brake hardware, and axle studs. I then went to a ZJ and pulled the soft brake lines from the rear as well as the proportioning valve, spring, and cap. My new parts order from rockauto looks like this:

1998 Jeep Grand Cherokee
Raybestos 76451R Rotors x 2
1999 Jeep Cherokee
PTC 97053 Front Lug Studs x 10
USA Std Gear USA30201 Wheel Seal x 2
WJB WB6408 Wheel Bearing x 2
2006 Jeep Liberty
AC Delco 18P2802 Parking Brake Cable (L)
AC Delco 18P2659 Parking Brake Cable (R)
Carlson H94022 Brake Bleeder Screw x 2
Carlson 41208 Caliper Repair Kit x 2
Centric 10309640 Brake Pads
Centric 11107450 Parking Brake Shoes
Raybestos H7346 Parking Brake Hardware KIt

Hope I didn't leave anything out! Everything will be in by Wed Aug 3 and I should have this job done by the end of the following weekend. I will be recording for a future youtube update.

Todd
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Old Jul 29, 2022 | 11:33 AM
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Some don't have a choice of which to ones to get due to lack of access. When I decided to covert mine I went to the only two salvage yards nearby and could get neither ZJ or KJ parts. Two hours to the next two. So I got a complete ZJ kit here from Big David who at that time was offering only ZJ ones. Get what you can. Modifying my ZJ ones were done as a part of cleaning them before painting. It's just that simple.

Your going to LIKE those disc brakes!
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Old Jul 29, 2022 | 11:39 AM
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Originally Posted by EZEARL
Some don't have a choice of which to ones to get due to lack of access. When I decided to covert mine I went to the only two salvage yards nearby and could get neither ZJ or KJ parts. Two hours to the next two. So I got a complete ZJ kit here from Big David who at that time was offering only ZJ ones. Get what you can. Modifying my ZJ ones were done as a part of cleaning them before painting. It's just that simple.

Your going to LIKE those disc brakes!
Good points! I sometimes do not realize how fortunate I am to have several yards in relatively close proximity who offer vehicles I'm looking for.
I can't wait to get this job underway! I've already cleaned and painted the calipers, cleaning and prepping the backing plates being next on the list.

Todd
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Old Jul 29, 2022 | 11:49 AM
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Funny thing is my next nearby neighbor has had a wrecked ZJ sitting since before I decided on doing the mod back in 2016. STILL there after saying he's going to "fix it up". That happens a lot around here with all kinds of stuff.
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Old Sep 22, 2022 | 12:48 PM
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MrTodd
a few questions. I am doing this Mod to a 94 XJ with Chrysler 8.25 axle. Have 2005 backing plates coming in mail. you have 3 parts listed for 99 XJ. do I need to get those parts for 94 or will 99 parts work. Also you said to pull soft brake lines and proportioning valve with guts from the ZJ. can i get those off any year ZJ or can i get them new and what year would I use if I got them new.
Thanks
Skp
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Old Sep 22, 2022 | 01:03 PM
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Originally Posted by Skp
MrTodd
a few questions. I am doing this Mod to a 94 XJ with Chrysler 8.25 axle. Have 2005 backing plates coming in mail. you have 3 parts listed for 99 XJ. do I need to get those parts for 94 or will 99 parts work. Also you said to pull soft brake lines and proportioning valve with guts from the ZJ. can i get those off any year ZJ or can i get them new and what year would I use if I got them new.
Thanks
Skp
ZJ = 93-98 yes, any of these years
get the bearings and seals for your axle, 94 is fine as long as it is the Chrysler 8.25
get the wheel studs from a Dana 30. 1999 is what I chose.

good luck!

todd
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